RFR: 8263464: NMT: assert in gtest os.release_multi_mappings_vm

Thu May 4 19:45:17 UTC 2023

This fix allows NMT to account for released memory that was allocated in chunks, as long as the final pointer and size refer to total contiguous regions of the requested size.

Tested via `Mach5 tier1,tier2,tier3` and locally via `gtest:NMT*:os*`

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Commit messages:
 - release memory reserved using multiple region allocations

Changes: https://git.openjdk.org/jdk/pull/13813/files
 Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=13813&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8263464
  Stats: 56 lines in 2 files changed: 32 ins; 19 del; 5 mod
  Patch: https://git.openjdk.org/jdk/pull/13813.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/13813/head:pull/13813

PR: https://git.openjdk.org/jdk/pull/13813